Intravitreal injection of low-dose gentamicin for the treatment of recurrent or persistent uveitis in horses: Preliminary results.

Abstract

BackgroundDespite appropriate medical therapy, many horses with equine recurrent uveitis continue to suffer from recurrent bouts of inflammation. Surgical intervention via the pars plana vitrectomy or suprachoroidal cyclosporine implant placement may control and/or prevent recurrences, however, these procedures may be contraindicated, unavailable, or declined by an owner. Thus, an effective adjunctive treatment option may help to improve the clinical outcomes in those situations. There are several anecdotal reports on the use of intravitreal gentamicin injections, but to date, no data evaluating the complication rate and/or treatment effect following this treatment have been published. Thus, the aim of this prospective study was to describe the intravitreal gentamicin injection technique, describe the associated peri-injection (within 24 h) and post-injection (30 to 780 days) complications, and to report the effects of the injection on the clinical signs of uveitis. Additionally, evaluation of the systemic and ocular Leptospira-status, and its effect on the treatment outcome was performed. A total of 86 horses of various ages, breeds, and gender presenting with recurrent or persistent uveitis were treated via intravitreal injection of 4 mg of undiluted gentamicin (0.04 ml, Genta 100, 100 mg/ml in 35 horses) or preservative-free gentamicin (0.05 ml, 80 mg/ml in 52 horses) under sedation and local anesthesia. All 86 horses were observed for immediate peri-injection and post-injection complications. Response to therapy was evaluated in 59 of the 86 horses (follow-up: 30 to 780 days).ResultsPeri-injection complications consisted of subconjunctival (26/86; 30.2%) or intracameral hemorrhage (4/86; 4.7%); both of which completely resolved within 5 days. Post-injection complications consisted of cataract formation/maturation (5/59 horses, 8.5%) and diffuse retinal degeneration (3/59 eyes 5.1%). The majority of horses 52/59 (88.1%) with a minimum follow-up period of 30 days were controlled (absence of recurrent or persistent inflammation) at their last recheck examination. Recurrent inflammation was documented in 5/59 (8.5%) horses and persistent inflammation was diagnosed in 2/59 (3.4%) horses.ConclusionsIntravitreal injection of low-dose gentamicin shows promise at controlling different types and stages of uveitis. The ability of intravitreal injections of low-dose gentamicin (4 mg) to control persistent and recurrent inflammation warrants further investigation.

Arthritis, panuveitis and hyperaesthesia associated with Borrelia afzelii infection in a warmblood gelding

“…It can be speculated whether achieved doxycycline concentrations in the current case induced an ocular anti-inflammatory effect. Similar considerations hold true for the low-dose intravitreal gentamicin (4 mg) injection, which successfully controlled different stages of inflammation in horses with recurrent or persistent uveitis 38. In a second case series,39 potential antibiotic properties addressing leptospiral-induced ERU have been suggested.…”

Long-term ophthalmologic examinations of eyes with equine recurrent uveitis after pars plana vitrectomy

“…The currently most promising alternative treatment option of equine recurrent uveitis is the intravitreal injection of low-dose gentamicin. A recent study shows that up to 88,1 % of 59 horses that received 4 mg of intravitreal gentamicin did not show recurrent or persistent ocular inflammation with a minimum of 30 days between treatment and follow-up (Fischer et al 2019). And another study showed that 91,8 % (56 of 61) treated eyes did not show ocular inflammation over a period that ranged between two and 96 months after treatment (Kleinpeter et al 2019).…”

“…Dwyer et al described that Appaloosas have an 8.3 times higher chance of developing uveitis than other equine breeds (Dwyer et al 1995). A recent study showed that Appaloosas with equine recurrent uveitis had a significant risk of developing recurrences after intravitreal treatment with low-dose gentamicin (Fischer et al 2019) and another study showed that leopard colored horses had a significantly higher risk to have a REC after vitrectomy (Schinagl 2017). One study evaluated the genetic risk factors for Appaloosas, such as a marker in the TRPM1 gene in the ECA1 region responsible for their spotted coat color and two different markers in the region for the equine major histocompatibility complex (Fritz et al 2014).…”

“…In addition to the acute therapy, only the prevention of future recurrences can effectively prevent further intraocular damage (Curling 2011). In addition to enucleation, vitrectomy, the implantation of a cyclosporine drug delivery device and intravitreal injection of a low-dose gentamicin are currently the only therapeutic modalities that may prevent recurrences (Werry and Gerhards 1991, Werry and Gerhards 1992, Winterberg and Gerhards 1997, Frühauf et al 1998, Gilger and Allen 1998, von Borstel et al 2005, Tömördy et al 2010, Dorrego-Keiter et al 2017, McMullen 2015, Kleinpeter et al 2019, Fischer et al 2019).…”

Highlights of recent clinically relevant papers

“…In this prospective study Britta Fischer and colleagues in the USA described an intravitreal gentamicin injection technique and the associated complications, and reported the effects of the injection on the clinical signs of uveitis .…”